The move comes a little over a year after Poncedeleon took a line drive to the head during a start in May 2017, an injury that required emergency brain surgery.
Poncedeleon didn't make another appearance over the remainder of the 2017 season.
The 26-year-old began 2018 with St. Louis' Triple-A affiliate, the Memphis Redbirds, and he's 5-2 with a 2.41 ERA in 59.2 innings. He has also struck out 71 batters but issued 35 free passes.
MLB.com doesn't list Poncedeleon among St. Louis' top 30 prospects, and MLB.com's Joe Trezza noted the odds were against him reaching the majors when he started his pro career:
While Poncedeleon has spent much of his time in the minors as a starter, The Athletic's Mark Saxon speculated the Cardinals may use him out of the bullpen.
Adam Wainwright and Alex Reyes are nursing injuries, but the starting rotation hasn't been much of an issue for St. Louis. Cardinals starting pitchers are fifth in FIP (3.55) and seventh in WAR (6.3), according to FanGraphs.
Poncedeleon could be utilized as a spot starter or long relief option in the likely event he doesn't crack the rotation.